In general, stents are expandable medical prostheses, and are used within body vessels of humans for a variety of medical applications. Examples include intravascular stents for treating stenosis, and stents for maintaining openings in the urinary, biliary, tracheobronchial, esophageal, and renal tracts, and inferior vena cava.
Typically, prior to placement, a stent will be maintained in a compressed state and delivered by a device designed to position the compressed stent at a treatment site, and then allow the stent to expand once in position. Commonly, stents are delivered to the treatment site by passage through the lumen of body vessels.
For example, in percutaneous transluminal angioplasty, an implantable endoprosthesis, that is, a stent is introduced through a delivery device, and is passed through body vessel conduits to a treatment site. After the stent approaches the treatment site, the stent is typically mechanically expanded, usually with the aid of an inflatable balloon, thereby being expanded within the body vessel. The delivery device is then retreated and removed from the patient. The stent remains within the vessel at the treatment site as an implant.